4-3 vs 3-4

Could someone please try to explain the benefits and shortcomings of the 3-4 vs 4-3. All I know is Bama runs a 3-4 however it looks like a 4-3. And they are sound. Which is better against run? Pass? On the surface it would appear to me the 3-4 might be more suited to defend today’s offenses. You need 3 behemoths in the middle. Instead of an end you have a hybrid linebacker/end type who can either rush or drop back. You have more speed on field. Seems that type player is easier to recruit rather than the prototype defensive end. On our team I’m thinking Randy Ramsey. You also clog up middle more with 2 inside linebackers. Then 2 outside to do whatever. But what do I know, that’s why I’m asking.